Wireless telephony.



A. PLISNIER, JR. WIRELESS TELEPHONY.

APPLIUATION FILED FEB. 12, 190e.

970,850. Y Patented Sept. 20, 1910.

UNITED PATENT OFFICE.

ALBERT PLISNIER, JR., OF STUTTGART, GERMANY, ASSIGNOR 0F ONE-HALF TO ARTHUR STEINACKER, OF FIUME, AUSTRIA-HUNGARY.

WIRELESS TELEPHONY.

Specification of Letters Patent.

Patented Sept. 20, 1910.

Application filed February 12, 1908. Serial No. 415,536.

To all whom it may concern:

Be it known that I, ALBERT PLIsNIEn, J r., subject of the Emperor of Austria-IIungary, residing at Stuttgart, in Viirtemberg, Germany, have invented certain new and useful Improvements Relating to Vireless Telephony, of which the following is a s ecilication.

This invention relates to wire ess telephony by means of undampened electric waves, and particularly to a switching arrangement therefor.

As is well known, to render wireless telephony possible by means of undampened waves, a microphone is switched in shunt to an inductance in the Duddel oscillating circuit. In this kind of switching, however, the electric-acoustic action upon the oscillating circuit is very small so that the corresponding curve of oscillation attains only very small amplitudes with the result that the waves sent are influenced very weakly by speech. Further, the life of a microphone in a strong current by direct switching to the poles of the self-induction coil where the greatest tension prevails is very short, or very high tension currents pass through the microphone, so that the latter becomes useless in view of the great heat developed and finally burns out. The present invention overcomes these disad uintages and embodies a circuit in shunt consisting of a microphone and capacity switched to the poles of a self-induction coil of the oscillating circuit and connected with the earth in the center between the microphone and capacity. By this means very great fluctuations of current are produced even if the operator in speaking uses a soft voice or tones, and the heating of the microphone is avoided, so that it is always operative and its life is therefore prolonged.

The advantages obtained by the present invention may be explained by occurrences as follows: First: by switching a regulable condenser into the microphone circuit an operator is enabled to diminish the tension upon the microphone as desired or to change the same in any manner. Second: the two points to which the microphone and the condenser circuit are connected on the coil must be considered as the poles furnishing the tension, or source of supply, for this circuit across the microphone and condenser. The

ohmic resistance w of the microphone is made equal to reactance w1 of capacity of the condenser so that 1U, equals we, consequently z' intensity at the microphone would also be equal to 2 intensity at the condenser and very slight changes of fw, as trials have shown, produce very great fluctuations in the microphone and condenser circuit.

The Duddel oscillating circuit may be fed by any kind of exciter of current waves, for instance, by a mercury vapor lamp spark gap with a cooperating high tension alternating current, or by an electric arc fed by a high tension direct current.

In the accompanying drawings :--Figure l illustrates a diagrammatic View of an organization for producing undampened eleetrical waves and embodying the features of the invention. Fig. Q is a similar view showing a different arrangement.

Referring to Fig. l, the aerial is directly and electrically excited and the reference character a designates an alternating current supply; Z) a high tension transformer; c a mercury vapor lamp spark gap, and the oscillating circuit consists of a condenser c and a self-induction coil f. W'ith the poles of the coil f, the circuit in shunt consists of a microphone i and rotary condenser 7c which are connected to the said coil poles. The aerial is designated by g, and l1. is the earth or an electrical counterweight connection which is made, as shown, in the center between the microphone and capacity.

In Fig. 2 the aerial is inductively, or magnetically, excited, the direct current being furnished by a high tension storage battery a and passes through the choking coils b and feeds the electric arc c which excites the oscillating' circuit consisting of capacity e and self-induction coil f. 'Io this Duddel circuit a second coil 7a2 is inductively and loosely coupled, and to this second coil the aerial g and earth orcounterweight 7L are connected. The arrangement or switching of the microphone i and the rotaryV condenser 7c is the same as shown by Fig. 1.

What is claimed is:

A switching organization for wireless telephony by means of undampened electric waves, consisting of an oscillating circuit embodying a self-induction coil, and a shunt circuit embodying a microphone and capacity switched to the poles of the seif-in- In testimony wfhereof I have hereunto Set duction coil and earthed at a point between 'my hand in presence of two Subscribing the said microphone and capacity, whereby Wltnesses.

the tension on the microphone may be ALBERT PLISNIER, JUN. changed or diminished at Will and the elec- Vitnessesf tric-acoustic action of the oscillating circuit OSCAR DI'ETERior-r,

may be increased. OSWALD BOMBORN. 

